【作者】 赵阳；

【导师】 路艳罗；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 硕士

【摘要】 本文分别合成了两种金属体系(Mg-Al;Zn-Al),不同M2+/M3+比例(2：1、3：1、4：1),不同客体(CO32-、NO3-、EDTA)插层的水滑石,利用XRD、IR、BET、SEM等多种表征手段研究了水滑石的结构,随后以水滑石为吸附剂对水中的Ni2+进行吸附实验。利用ICP确定溶液中Ni2+浓度随时间的变化,并对吸附过程进行动力学拟合,研究了水滑石对Ni2+的吸附规律。由共沉淀法制备了Zn/Al投料比为(2：1,3：1,4：1),不同客体离子(CO32-, NO3-, EDTA)插层的LDHs,具有典型的水滑石层状结构,层间距的变化和FT-IT谱图表明CO32-, NO3-, EDTA分别插层成功。进而进行了吸附实验,Zn/Al投料比为(2：1)的ZnAl-CO3-LDHs具有最大的去除率,可达96%,其平衡吸附量可达19mg/g；利用动力学方程拟合其吸附过程,水滑石对于Ni2+的吸附过程符合准二级方程,表明LDHs与Ni2+的化学作用是吸附过程的速控步骤。Zn/Al投料比为(4：1)的ZnAl-EDTA-LDHs的吸附速率常数K2最大,可达0.12g·mg-1·min-1。同样方法制备了Mg-Al体系的水滑石,并对其结构和吸附性能进行了表征,具有典型的水滑石层状结构,层间距的变化和FT-IT谱图表明CO32-,NO3-, EDTA分别插层成功。去除率最大的为Mg/Al投料比为(3：1)的MgAl-CO3-LDHs,其平衡吸附量可达84mg/g,用准二级动力学方程拟合Mg-Al体系对于Ni2+的吸附过程,其相关系数可无限趋近于1。而Mg/Al投料比为(2：1)的MgAl-NO3-LDHs的准二级吸附速率常数可达0.05g·mg-1·min-1, MgAl-EDTA-LDHs在3min内即可完成其快速吸附过程,5mmin左右达到吸附平衡。综上所述,比表面积较大的水滑石是较好的Ni2+吸附剂,吸附速率较快,吸附量较大,特别是C032-插层的水滑石作为吸附剂,200min之内就能达到平衡,处理后的水溶液中Ni2+浓度最低达到0.0084 mg/L,远小于GB8978-2002中规定的0.5mg/L的排放标准。因此,水滑石有望于日后应用于含Ni2+废水的处理中。更多还原

【Abstract】 In this paper, ZnAl-LDHs and MgAl-LDHs intercalated with CO32-, NO3-, EDTA were synthesized by coprecipitation method. XRD, IR, BET, and SEM were used to characterize the structure and morphology of LDHs. The samples were added to the solution of Ni(NO3)2·6H2O in order to study the adsorption properties. The concentration of Ni2+ was examined at real-time by ICP analysis. The adsorption kinetics were studied.The XRD patterns are characteristic of a layered phase with the basal diffraction due to planes (003), (006) and (110). FT-IR spectra indicate that CO32-, NO3- and EDTA were intercalated between the layers respectively. As the specific surface of the LDHs increase, the saturated adsorptive capacity increases. ZnAl-CO3-LDHs (Zn/Al molar ratio=2) has the maximum capacity, up to 19 mg/g, that is about 96% Ni2+ in the solution. The Pseudo second equation can perfectly fit the Ni2+ adsorption process on LDHs, indicates a chemispoption mechanism being the rate-determining step.Mg-Al LDHs have a characteristic layered structure, and CO32-, NO3- and EDTA were intercalated between the layers respectively. CO3-LDHs with the molar ratio of (3:1) which has the maximum adsorptive capacity about 84 mg/g.As An adsorptive material of Ni2+, the LDHs with big specific surface have favourable properties. Especially the MgAl-CO3-LDHs can reduce the Ni2+ concentration to 0.0087 mg/L which is much less than the standard 0.5mg/L of GB8978-2002. Obviously, LDHs can be expected to put in fact in the treatment of Ni2+ contained in the wastewater.更多还原